924Board.org

[firemn131]

I recently changed to synth.
I am seeing alot of leaks now. Is it ok to go back to the original oil?

Any suggestions on grades.
I live in Maryland with temps fairly stable during the 4 seasons.

John

[Paul]

Yes go back to 15W-50 dino oil, but don't expect the leaks to stop completely.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

[jrrhdmust]

The reason you see leaks with a synthetic and not dino, is the synthetic has a lot more detergents in them. They literally clean the engine. So the synthetic cleaned all the deposits that were keeping your seals from leaking.

So going back to a dino oil will not harm the car, but it won't stop the leaks immediately either.
_________________
67 Mercury Cougar XR7 under Restoration
71 VW Superbeetle Completed Resto 11/07
73 Mustang Mach 1 10 Year old restoration

[mehall]

For those interested:

Synthetics, especially the di-ester types (made from plants, esp. corn) such as Amsoil, are usually given an additive package with high detergent levels because people tend to leave the oil in the car for up to 25,000 miles. Because normal combustion blow-by creates acids in the oil, the detergent is there to neutralize it.

Therefore, it will clean out your false seals, showing you exactly where you need to provide service. But the real problem in older engines is that the chemical structure that gives di-ester oil extreme levels of lubrication (leading to higher hp at the wheels and better fuel economy) also create a proclivity to leaking out of your engine/tranny/differential. This oil adheres to metal so well that it will actually climb up the interior to an existing hole and seep out.

Di-ester oils are far superior to even other "synthetics," which are made from the all pervasive dino oil, because they do not break down under extreme conditions until you maintain block temps over 600+ degrees. But the manufactureres of those products all recommend that you have good seals and not to put it in an engine with over 100,000 miles unless its been already using their type of oil.

To provide most of the benefits of synthetic oil, most companies offer a blend of syn and dino, which is uniformly recommended for older engines.

Hope this helps. I have a background in selling synthetics to many truck firms and racing teams back in the late 70s & early 80s.

Mark
_________________
Mark

'87 White 924s manual
'94 Lexus LS400

www.kcws.org